Duct joining systems are well known in the art and generally are utilized to join together the ends of adjacent duct sections such as heating and air conditioning ducts or the like. Such systems typically include couplers respectively fastened to the end edges of each of the walls forming the duct. In a general sense, each of the couplers is defined by an elongated channel adjacent each corner and an L-shaped corner connector with each leg coupled to one of the elongated channels adjacent each corner. When two of the L-shaped corner connectors, and thus the duct ends, are brought together in an abutting relationship, they can be attached together thus attaching the ends of the ducts together. Representative prior art illustrating such type of construction include: my copending U.S. patent application Ser. No. 478,238, filed Feb. 9, 1990, entitled "Duct Joining System" now U.S. Pat. No. 5,069,484; U.S. Pat. No. 4,636,105, Johansson, issued Jan. 13, 1987; U.S. Pat. No. 4,558,892, Daw et. al., issued Dec. 17, 1985, U.S. Pat. No. 4,542,923, La Crosse et. al., issued Sept. 24, 1985; and U.S. Pat. No. 3,199,901, Jeppsson, issued Aug. 10, 1965.
The system disclosed in my co-pending patent application is an excellent system designed for use with duct rated for low pressure applications, but it may have limited use in high pressure applications. Each of the other prior art systems have some disadvantage, such as, the ineffectiveness of the assembly system, the cost of manufacture, the cost of installation, or the difficulty in installation. Obviously, when the amount of time required to install the L-shaped connectors increases, the cost of the job increases. Thus, it is important to provide a system for interconnecting ducts that provides connecting elements that are economical and simple to manufacture, and that are easily and quickly installed to complete the installation.
The present system provides a new and unique L-shaped corner connector design that permits the boltless connectors to be quickly, easily and positively locked to each other resulting in a connection that is strong enough for all ducts, regardless of the pressure rating. Also, the system of the invention is useable in either an integral flange duct system or in a slip-on or picture frame flange system. Although the invention obviates the use of a bolt or other type of separate fastener, the design of the invention permits the use of a bolt if desired. Each of the L-shaped connectors has an irregular shaped opening at the juncture of the legs of the connector. This opening is shaped to provide a wide center portion and a narrower slot. A T-shaped tab is integrally formed with and extends inwardly from the peripheral edge of the opening opposite the slot. When a corner connector is reversed in position and placed in superimposed abutting relationship with a second connector, the tabs are on opposing peripheral edges of the openings in the two connectors. This allows the tab on each connector to be inserted through the wider center portion of the opening in the other connector, and then bent over into the slot of the other connector. Because of the T-shape of the tabs, the two connectors will be positively locked together.
A score line may be formed at the base of each tab on the outside surface of the connector to allow the tab to be easily bent over after insertion through the opening of the abutting connector to lock the connectors together.
The novel construction allows for the use of bolt in addition to the locking features of the connector. If bolts are used, the locking tabs can either be cut off or bent out of the way and a bolt installed.
As is well known to those skilled in the art, the legs of each of the L-shaped connectors are flat metal strips the edges of which are turned toward the inside surface to provide stiffening ribs and to aid in attachment to the duct piece when used with either a picture-frame type connecting system or an integrally rolled flange connecting system, both systems being well-known in the art.
Thus, it is an object of the present invention to provide a duct joining system that is effective in achieving an improved coupling in a quick fashion when the duct ends are joined together.
It is also an object of the invention to provide a duct joining system in which no special pins are required to join the duct ends.
It is yet another object of the invention to provide a method of joining duct ends with the use of connectors that lock together in a simple manner without the use of special tools.
It is still another object of the present invention to provide an improved L-shaped connector for use in joining the ends of ducts, including ducts rated for high pressure applications.